This invention relates to a circular saw, and particularly relates to a circular saw which includes facility for alignment of a saw blade thereof during the cutting of a workpiece, and for managing the disbursement of chips of the workpiece resulting from the cutting of the workpiece upon use of the saw.
A circular saw includes a generally circular saw blade having cutting teeth or tips located radially about the periphery of the blade. The blade is mounted on a housing of the saw and is rotatably driven during the cutting of a workpiece, under the control of a user or operator of the circular saw. The circular saw also typically includes an upper guard which is fixedly located about an upper portion of the blade to preclude contact with the upper portion of the blade by anyone who is handling or using the saw to form kerfs in the workpiece. In some instances, a lower guard is located about a lower portion of the blade and precludes contact, by a handler or operator, with the blade when the blade is at rest or is being rotated but not placed in a position to form a kerf in the workpiece. The lower guard is mounted to the housing for rotary, or swinging, movement when the saw is manipulated to move the rotating blade into cutting engagement with the workpiece.
In some instances, a flat plate is attached to the housing of the circular saw and is formed with an opening therethrough. The blade is mounted to then housing in such a manner that a first portion of the blade extends outward from the opening and a first major side of the plate, and a second portion of the blade extends from the opening and a second major side of the plate. The flat plate provides a guiding surface which the operator of the saw can position on the workpiece to facilitate control of the circular saw during a cutting operation.
When the circular saw is used to form a kerf in the workpiece, the portions of the workpiece, which are being removed by the rotating blade, separate from the workpiece in the form of chips. The resulting chips are dispersed from the blade-cutting area, and scatter in random directions.
When the workpiece is composed of wood, the chips are heated to some extent as a natural result of the chips being separated from the workpiece by the blade. However, as the chips are being dispersed from the cutting area, the heat thereof is quickly dissipated, and any dispersed chips which may eventually strike an exposed skin area of the operator, or others nearby, are usually cooled sufficiently to be harmless, provided the operator and others nearby are wearing safety glasses. If the workpiece is composed of metal, the dispersed metal chips tend to retain the heat developed during the formation of the kerf. As the heated metal chips are randomly dispersed, many of the chips will strike the operator and could injure exposed skin areas of the operator.
Thus, there is a need for a circular saw which will effectively manage the dispersement of chips, particularly when the saw is used to cut metal, to insure that the chips are discharged in a direction which avoids contact with the operator.
Prior to using a saw to form a kerf in the workpiece, the operator may place guide lines on a surface of the workpiece which define the location of the kerf to be formed. The operator then moves the blade along the guide lines when using the circular saw to form the kerf. In a circular saw which includes the flat plate, the plate may cover all or a portion of the guide lines and thereby obstruct the view of the operator. Circular saws have been designed with a notch or second opening formed in the flat plate, forward of the blade, to provide some opportunity for the operator to see the guide lines during the cutting operation. For example, U.S. Pat. No. 4,856,394, which issued on Aug. 15, 1989, shows a circular saw having a notch formed in a forward edge of a shoe thereof, while U.S. Pat. No. 4,555,849, which issued on Dec. 3, 1985, shows a circular saw formed with a perforation through a forward portion of a flat plate.
While the notch or perforation noted above provide some opportunity for the operator to see guide marks on the workpiece during a kerf-forming operation, a major portion of the guide marks remain obstructed during the operation.
Thus, there is a need for a circular saw with a facility for providing effective kerf-forming guidance for an operator of the saw which includes a shoe with portions extending forward of the blade thereof.